It is increasingly incumbent upon ministries of education to build evaluation into new programs – especially those programs where substantial amounts of money are being spent. Each new program will usually be accompanied by questions about the impact and effectiveness of the program. This booklet is about small-scale and large-scale program evaluation studies. In many cases, both small- and large-scale studies are needed within any one evaluation project. In this booklet the authors argue that there is a need for both kinds of studies – provided that they are conducted according to scientific standards.